\begin{tikzpicture} % 复杂
    \pgfmathsetmacro{\R}{1}
    \pgfmathsetmacro{\RR}{sqrt(2)*\R}

    \tkzDefPoints{0/0/O}
    \tkzDefPoint(0:\R){A}
    \tkzDefRegPolygon[center,sides=4,name=P](O,A)
    \tkzDefPoint(45:\RR){B}
    \tkzDefRegPolygon[center,sides=4,name=Q](O,B)
    % \tkzLabelPoints[centered](P1,P...,P4)
    % \tkzLabelPoints[centered](Q1,Q...,Q4)

    % \tkzDrawSegments[dashed](P1,P3  P2,P4)
    \tkzDrawPolygon[thick](Q1,Q...,Q4)

    \foreach \i in {1,...,4} {
        \ifnum\i=4\relax
            \pgfmathsetmacro{\n}{1}
        \else
            \pgfmathsetmacro{\n}{int(\i+1)}
        \fi

        \begin{scope}
            \tkzClipSector(P\i,Q\i)(O)
            \tkzClipSector(P\n,O)(Q\i)
            \tkzFillPolygon[pattern={mylines[angle=65, distance={3pt}]}](P\i,Q\i,P\n,O)
            \tkzDrawArc[thick](P\i,Q\i)(O)
            \tkzDrawArc[thick](P\n,O)(Q\i)
        \end{scope}
    }

    \tkzDrawSegments[dim={$a$,-1em,}](Q3,Q4)
\end{tikzpicture}

